JP-A-2002-367732 (Patent Literature 1) describes one example of a connector having a lock mechanism using a shell. The connector of this type has been utilized as an interface of electronic equipment such as a mobile phone, a PDA, or a personal computer. For these types of electronic equipment, high-speed signal operation has been developed day by day. The shell is provided, so that a characteristic impedance can be adjusted and a shield effect against electromagnetic wave noise from the outside can be obtained. Patent Literature 1 further describes that the lock mechanism is provided at the shell to suppress casual cancellation of fitting.
An exploded perspective view of a connector 100 disclosed in Patent Literature 1 is illustrated in FIG. 12. Note that an outer hood is not shown in this figure. The connector 100 mainly includes an insulator 103 and a base shell 101 and a cover shell 102 covering the insulator 103. The base shell 101 is formed from a single metal plate. The base shell 101 includes a flat plate 111 as a ceiling plate, side pieces 112 bent at right angle on lateral sides of the flat plate 111, and arms 113 coupled to the side pieces 112 and supported in a cantilever manner. An engagement piece 113a is provided in the vicinity of a tip end of each arm 113, and upon fitting to a partner connector (not shown), such a portion functions as a portion configured to engage with a predetermined portion of the partner connector to lock fitting to the partner connector.
The arm 113 and the side piece 112 are coupled together with a coupling portion turning in a U-shape. In Patent Literature 1, such a coupling portion is positioned at the hack (the opposite side of the direction of fitting to the partner connector) of the arm 113, and therefore, a distance between a free end of the arm and the coupling portion increases. This leads to, e.g., problems that it is difficult to provide sufficient elastic force to the arm and it is difficult to adjust elastic force. Moreover, since the arms 113 are formed, a long plate material for each arm 113 is, for a flat metal plate before processing of the arm such as bending, necessary on the back side (the opposite side of the side of fitting to the partner connector) of the coupling portion coupling the arm 113 and the side piece 112. As a result, the plate material has been used uselessly.